Supergirl/Flash crossover poster & details revealed

The epic crossover between The CW’s Flash and CBS’ Supergirl hits American screens in just under three weeks, and Warner Bros. TV have stepped up the promotion for the event.

A new comic-book cover-esque poster has been released depicting Supergirl (Melissa Benoist) and Grant Gustin as the Flash (as well as the Supergirl supporting cast). The episode is written by Andrew Kreisberg and Michael Grassi from a story by Greg Berlanti, and is directed by Nick Gomez.

The official logline explains that Kara gains a new ally when the lightning-fast superhero The Flash (Grant Gustin) suddenly appears from an alternate universe and helps Kara battle Siobhan, aka Silver Banshee, and Livewire in exchange for her help in finding a way to return him home. (For the benefit of UK readers, who are now a number of episodes behind, we’ve hidden the details of the opponents, as they’re spoilers for episodes 14 and 15.

World’s Finest airs in the US on March 28; it should hit Sky towards the end of May.